base: new session-creation helper types

This patch augments the existing session/session.h with useful types for
the session creation:

* The new 'Insufficient_ram_quota' and 'Insufficient_cap_quota'
  exceptions are meant to supersede the old 'Quota_exceeded' exception
  of the 'Parent' and 'Root' interfaces.

* The 'Session::Resources' struct subsumes the information about the
  session quota provided by the client.

* The boolean 'Session::Diag' type will allow sessions to operate in a
  diagnostic mode.

* The existing 'Session_label' is not also available under the alias
  'Session::Label'.

* A few helper functions ease the extraction of typed session arguments
  from the session-argument string.

Issue #2398

repos/base/include/session/session.h

@@ -14,6 +14,10 @@
 #ifndef _INCLUDE__SESSION__SESSION_H_
 #define _INCLUDE__SESSION__SESSION_H_
 
+#include <base/quota_guard.h>
+#include <base/session_label.h>
+#include <util/arg_string.h>
+
 /*
  * Each session interface declares an RPC interface and, therefore, relies on
  * the RPC framework. By including 'base/rpc.h' here, we relieve the interfaces
@@ -21,7 +25,16 @@
  */
 #include <base/rpc.h>
 
-namespace Genode { struct Session; }
+namespace Genode {
+
+	struct Session;
+
+	/*
+	 * Exceptions that may occur during the session creation
+	 */
+	struct Insufficient_ram_quota : Exception { };
+	struct Insufficient_cap_quota : Exception { };
+}
 
 
 /**
@@ -29,6 +42,16 @@ namespace Genode { struct Session; }
  */
 struct Genode::Session
 {
+	struct Resources
+	{
+		Ram_quota ram_quota;
+		Cap_quota cap_quota;
+	};
+
+	struct Diag { bool enabled; };
+
+	typedef Session_label Label;
+
 	/*
 	 * Each session interface must implement the class function 'service_name'
 	 * ! static const char *service_name();
@@ -39,4 +62,33 @@ struct Genode::Session
 	virtual ~Session() { }
 };
 
+
+namespace Genode {
+
+	static inline Ram_quota ram_quota_from_args(char const *args)
+	{
+		return { Arg_string::find_arg(args, "ram_quota").ulong_value(0) };
+	}
+
+	static inline Cap_quota cap_quota_from_args(char const *args)
+	{
+		return { Arg_string::find_arg(args, "cap_quota").ulong_value(0) };
+	}
+
+	static inline Session::Label session_label_from_args(char const *args)
+	{
+		return label_from_args(args);
+	}
+
+	static inline Session::Resources session_resources_from_args(char const *args)
+	{
+		return { ram_quota_from_args(args), cap_quota_from_args(args) };
+	}
+
+	static inline Session::Diag session_diag_from_args(char const *args)
+	{
+		return { Arg_string::find_arg(args, "diag").bool_value(false) };
+	}
+}
+
 #endif /* _INCLUDE__SESSION__SESSION_H_ */

repos/os/src/init/types.h

@@ -25,8 +25,6 @@ namespace Init {
 	using Genode::size_t;
 	using Genode::strlen;
 
-	struct Ram_quota { size_t value; };
-
 	struct Prio_levels { long value; };
 
 	typedef List<List_element<Init::Child> > Child_list;